Difference in postmortem degradation pattern among troponin T isoforms expressed in bovine longissimus, diaphragm, and masseter muscles

Physicochemical composition, fatty acid profile and sensory attributes of meat (longissimus lumborum muscle) from Nellore and Nellore-cross bulls

This study aimed to compare the physicochemical characteristics, fatty acid composition, and sensory attributes of the meat from three genetic groups: Nellore (Nell), ½ Nellore × ½ Angus (NeAn), and ¼ Nellore × ¼ Angus × ½ Senepol (NASe). Longissimus lumborum muscle from 30 slaughtered bulls with a body weight of 549 ± 32.5 kg was used. The water holding capacity was greater for the Nell and NeAn groups than for the NASe group. Meat samples from the NASe group exhibited a higher L* index than those from the NeAn group and lower a* and b* color indexes than those from the Nell group. The meat fatty acid profiles showed that the Nell group had higher concentrations of 12:0, 14:0, 18:1 t11, 14:1 c9, 16:1 c9, 18:1 c9, 18:1 c11, 18:2 c9, t11 (conjugated linoleic acid (CLA)), and 20:3 n-6 polyunsaturated fatty acid (PUFA) than the NeAn and NASe groups. The total saturated (ΣSFA), unsaturated (ΣUFA), and monounsaturated (ΣMUFA) fatty acid concentrations were higher and the ΣPUFA:ΣSFA ratio was lower in the Nell group than in the NeAn group. The Δ⁹-desaturase C16 activity was significantly higher in the Nell and NASe groups than in the NeAn group. The atherogenicity index (AI) tended to be lower in the crossbreeds than in the Nell breed. The NASe group presented meat with better tenderness, juiciness, and overall acceptance than the Nell and NeAn groups and was therefore the best genetic group for beef production of the tested groups.

Myosin heavy chain isoform and metabolic profile differ in beef steaks varying in tenderness

Our objective was to investigate possible differences in muscle fiber characteristics of beef longissimus lumborum (LL) steaks varying in tenderness (very tender vs. intermediate tender). Therefore, the relative abundance of myosin heavy chain (MHC) isoforms and activity/abundance of several glycolytic and oxidative enzymes were compared between the two steak groups. Greater (P < 0.05) content of MHC type IIa (MHC-IIa) and activities of phosphofructokinase (PFK) and glycogen phosphorylase (GP) were observed in the very tender steaks. Conversely, intermediate tender steaks had greater (P < 0.05) contents of MHC type I (MHC-I) and succinate dehydrogenase (SDH) and greater citrate synthase (CS) activity. Increased tenderness in the very tender steaks was associated with greater (P < 0.05) proteolysis as evaluated by desmin and troponin-T degradation. Further, mitochondrial calcium uniporter (MCU) was lower (P < 0.05) in the very tender steaks than steaks of intermediate tenderness. Collectively, shifting muscle characteristics toward a more glycolytic type appears to positively impact postmortem proteolysis and tenderization.

MEATabolomics: Muscle and Meat Metabolomics in Domestic Animals

In the past decades, metabolomics has been used to comprehensively understand a variety of food materials for improvement and assessment of food quality. Farm animal skeletal muscles and meat are one of the major targets of metabolomics for the characterization of meat and the exploration of biomarkers in the production system. For identification of potential biomarkers to control meat quality, studies of animal muscles and meat with metabolomics (MEATabolomics) has been conducted in combination with analyses of meat quality traits, focusing on specific factors associated with animal genetic background and sensory scores, or conditions in feeding system and treatments of meat in the processes such as postmortem storage, processing, and hygiene control. Currently, most of MEATabolomics approaches combine separation techniques (gas or liquid chromatography, and capillary electrophoresis)-mass spectrometry (MS) or nuclear magnetic resonance (NMR) approaches with the downstream multivariate analyses, depending on the polarity and/or hydrophobicity of the targeted metabolites. Studies employing these approaches provide useful information to monitor meat quality traits efficiently and to understand the genetic background and production system of animals behind the meat quality. MEATabolomics is expected to improve the knowledge and methodologies in animal breeding and feeding, meat storage and processing, and prediction of meat quality.

Glycolysis and pH Decline Terminate Prematurely in Oxidative Muscles despite the Presence of Excess Glycogen

Meat from oxidative skeletal muscle has a higher postmortem ultimate pH, which was originally thought to be a result from decreased antemortem glycogen stores. Therefore, we hypothesized that excess glycogen may not resolve the high ultimate pH of meat from oxidative muscles in ruminants and poultry. To test this hypothesis, an in vitro muscle glycolytic buffer system containing excess glycogen was used to compare glycolysis and pH decline of glycolytic and oxidative muscle from beef, lamb, chicken, and turkey. Glycogen concentration of both glycolytic and oxidative muscle homogenates was similar at 0 min and decreased significantly with time in all species tested. All homogenates contained residual glycogen at 1440 min, indicating glycogen was provided in excess. The ultimate pH of the oxidative muscle homogenates was significantly increased compared to the glycolytic muscle. The oxidative muscle also contained decreased lactate and decreased glucose 6-phosphate in all the species tested at 1440 min. Combined these data suggest that glycolysis and pH decline of oxidative muscles terminate prematurely at higher ultimate pH even in the presence of excess glycogen across livestock species. Additionally, the data indicated that the in vitro glycolytic buffer system can be used to study species specific meat quality problems in beef, lamb, chicken, and turkey.

Metabolomic approach to key metabolites characterizing postmortem aged loin muscle of Japanese Black (Wagyu) cattle

OBJECTIVE

Meat quality attributes in postmortem muscle tissues depend on skeletal muscle metabolites. The objective of this study was to determine the key metabolic compounds and pathways that are associated with postmortem aging and beef quality in Japanese Black cattle (JB; a Japanese Wagyu breed with highly marbled beef).

METHODS

Lean portions of Longissimus thoracis (LT: loin) muscle in 3 JB steers were collected at 0, 1, and 14 days after slaughter. The metabolomic profiles of the samples were analyzed by capillary electrophoresis time-of-flight mass spectrometry, followed by statistical and multivariate analyses with bioinformatics resources.

RESULTS

Among the total 171 annotated compounds, the contents of gluconic acid, gluconolactone, spermidine, and the nutritionally vital substances (choline, thiamine, and nicotinamide) were elevated through the course of postmortem aging. The contents of glycolytic compounds increased along with the generation of lactic acid as the beef aging progressed. Moreover, the contents of several dipeptides and 16 amino acids, including glutamate and aromatic and branched-chain amino acids, were elevated over time, suggesting postmortem protein degradation in the muscle. Adenosine triphosphate degradation also progressed, resulting in the generation of inosine, xanthine, and hypoxanthine via the temporal increase in inosine 5'-monophosphate. Cysteine-glutathione disulfide, thiamine, and choline increased over time during the postmortem muscle aging. In the Kyoto encyclopedia of genes and genomes database, a bioinformatics resource, the postmortem metabolomic changes in LT muscle were characterized as pathways mainly related to protein digestion, glycolysis, citric acid cycle, pyruvate metabolism, pentose phosphate metabolism, nicotinamide metabolism, glycerophospholipid metabolism, purine metabolism, and glutathione metabolism.

CONCLUSION

The compounds accumulating in aged beef were shown to be nutritionally vital substances and flavor components, as well as potential useful biomarkers of aging. The present metabolomic data during postmortem aging contribute to further understanding of the beef quality of JB and other breeds.

Changes in the colour and sensory properties of beef frozen after seven days of ageing in a modified atmosphere

The aim of the study was to evaluate the colour, sensory properties and shear force values of meat from ten young bulls produced by crossing Polish Black-and-White Holstein-Friesian cows with Belgian White Blue bulls. The quality of the longissimus lumborum (LL) muscle was determined after seven-day ageing under various modified atmosphere (MA) conditions (vacuum – group B; 40% CO2 + 60% N2 – group C; 30% CO2 + 70% Ar – group D) followed by freezing and frozen storage. The process of seven- day ageing in MA composed of 40% CO2 + 60% N2 significantly increased the colour lightness of the beef samples. Eight-month frozen storage increased colour lightness in the meat samples aged in MA composed of 30% CO2 + 70% Ar. Meat samples aged under various MA conditions had a higher contribution of redness (a*) and yellowness (b*) than non-aged beef. Meat samples frozen after ageing in MA containing Ar had less redness than the samples from other groups. After frozen storage, meat samples from all groups had less redness and yellowness. Ageing and frozen storage had no significant effect on the juiciness of the beef. The beef aged in vacuum conditions was the most tender, both before and after frozen storage. Ageing had no significant influence on the shear force of meat samples evaluated before freezing. Meat samples aged in MA composed of 30% CO2 + 70% Ar evaluated after frozen storage had lower average shear force values than beef that had not been aged prior to freezing.

Molecular cloning, structural analysis, and tissue expression of the TNNT3 gene in Guizhou black goat

The vertebrate fast skeletal troponin T (TNNT3) protein is an important regulatory and structural component of thin filaments in skeletal muscle, which improves meat quality traits of livestock and poultry. In this study, the troponin T isoforms from adult goat (skeletal muscle mRNA) were identified. We isolated the full-length coding sequence of the goat TNNT3 gene (GenBank: KM042888), analyzed its structure, and investigated its expression in different tissues from different aged goats (10, 30, 90, 180, and 360 days old). Real-time quantitative reverse transcription-polymerase chain reaction analyses revealed that Guizhou black goat TNNT3 was highly expressed in the biceps femoris muscle, abdominal muscle, and longissimus dorsi muscle (P<0.01), and lowly expressed in the cardiac muscle, masseter muscle, and rumen tissue (P>0.05). Western blotting confirmed that the TNNT3 protein was expressed in the muscle tissues listed above, with the highest level found in the longissimus dorsi muscle, and the lowest level in the masseter muscle. In the 10 to 360day study period the TNNT3 protein expression level was the highest when the goats were 30 days old. A peptide, ASPPPAEVPEVHEEVH that may contribute to improved goat meat tenderness was identified. This study provides an insight into the molecular structure of the vertebrate TNNT3 gene.

CE-TOF MS-based metabolomic profiling revealed characteristic metabolic pathways in postmortem porcine fast and slow type muscles

To determine key compounds and metabolic pathways associated with meat quality, we profiled metabolites in postmortem porcine longissimus lumborum (LL) and vastus intermedius (VI) muscles with different aging times by global metabolomics using capillary electrophoresis-time of flight mass spectrometry. Loading analyses of the principal component analysis showed that hydrophilic amino acids and β-alanine-related compounds contributed to the muscle type positively and negatively, respectively, whereas glycolytic and ATP degradation products contributed to aging time. At 168h postmortem, LL samples were characterized by abundance of combinations of amino acids, dipeptides, and glycolytic products, whereas the VI samples were characterized by abundance of both sulfur-containing compounds and amino acids. The AMP and inosine contents in the VI were approx. 10 times higher than those in the LL at 4h postmortem, suggesting different rates of inosine 5'-monophosphate (IMP) accumulation by adenylate kinase 7 and 5'-nucleotidase, and subsequent different production levels of IMP and hypoxanthine between these two porcine muscles.

Profiling of differentially expressed microRNA and the bioinformatic target gene analyses in bovine fast- and slow-type muscles by massively parallel sequencing

MicroRNA (miRNA) are highly conserved, noncoding small RNA involved in post-transcriptional gene regulation in a variety of biological processes. To elucidate roles of miRNA in bovine muscle type specification and maintenance, we sought to determine differentially expressed miRNA between semitendinosus (STD) and masseter (MS) muscles from 3 Japanese black cattle by massively parallel sequencing. Differential gene expression of myosin heavy chain (MyHC) isoforms confirmed that STD and MS were MyHC-2x- and MyHC-1-abundant muscles, respectively. In total, 192 known miRNA and 20 potential new bovine miRNA were obtained from the sequencing. The differentially expressed miRNA with more than 2-fold difference in each muscle were identified. In particular, miR-196a and miR-885 were exclusively expressed in STD muscle, which was validated by quantitative reverse transcription-PCR (P=0.045 and P<0.001, respectively), whereas a slow type-directing miR-208b was highly expressed in MS compared with STD (false discovery rate<0.05). In addition, 16 potential novel miRNA were mapped and confirmed for their precursor structures by computational analyses. The results of functional annotation combined with in silico target analysis showed that the predicted target genes of miR-196a/b and miR-885 enriched gene ontology (GO) terms related to skeletal system development and regulation of transcription, respectively. Moreover, GO terms enriched from predicted targets miRNA suggested that STD-abundant- and MS-abundant-miRNA were associated with embryonic body planning and organ/tissue pattern formation, respectively. The present results revealed that the differentially expressed miRNA between the STD and MS muscles may play key roles to determine muscle type-specific tissue formation and maintenance in cattle thorough attenuating putative target genes involved in different developmental events.

Identification of biomarkers of meat tenderisation and its use for early classification of Asturian beef into fast and late tenderising meat

BACKGROUND

The objective of this work was to study the post-mortem evolution of potential biomarkers (µ-calpain activity and proteolytic profile) of meat tenderisation in bovine longissimus dorsi (LD) muscle from several biotypes coming from two beef breeds ('Asturiana de los Valles' and 'Asturiana de la Montaña') and showing different levels of muscular hypertrophy (mh/mh, mh/+, + /+).

RESULTS

LD samples were taken at 2, 12, 24 and 48 h and 3, 7, 14 and 21 days post-mortem. The presence of muscular hypertrophy produced a faster rate of pH decline, faster exhaustion of µ-calpain activity and earlier occurrence of proteolytic changes. Changes in the electrophoretic pattern of some peptides from sarcoplasmic (glyceraldehyde-3-phosphate dehydrogenase) and myofibrillar (troponin T and troponin I) muscle extracts within the first 24 h significantly correlated with meat toughness and allowed accurate discrimination of meat products into two groups: (1) fast tenderising meat, coming from mh-biotypes, and (2) late tenderising meat, from normal (+/+) biotypes.

CONCLUSION

Early monitoring (within 24 h after slaughter) of selected biomarkers in LD muscle allowed accurate prediction of ultimate meat toughness and could be used in the meat industry as a tool for early classification of beef into fast and late tenderising meat.

Difference in tenderness and pH decline between water buffalo meat and beef during postmortem aging

The objective of this research was to determine the difference in tenderness and some characteristics of water buffalo meat and beef during postmortem aging. Five female crossbred water-buffalo (Philippine Carabao×Bulgarian Murrah) and five female crossbred cattle (Brahman×Philippine Native), were finished on the same diet for 6 months and slaughtered at 30 months of age. The muscle pH was measured at 40min, 3h, 7h, 24h, and 48h postmortem. Longissimus thoracis (LT) and semimembranosus (SM) muscles were excised at 2d postmortem, and shear force was measured at 2, 4, 7, and 14d postmortem. Glycogen and lactate concentrations were determined from 0, 2, and 4d LT samples, and myosin heavy chain type of buffalo and cattle LT was determined by ELISA methods. Myofibrillar protein degradation was also observed by SDS-PAGE and Western blotting of fast-type troponin T. Results showed that the buffalo meat had significantly lower shear force values compared to beef for LT and SM muscles, which was supported by a difference in troponin T degradation. Postmortem pH decline of buffalo meat was significantly slower than that of beef, which was confirmed by lactic acid concentrations, but was not explained by glycogen content. In addition, there was no significant difference in the ratio of slow to fast type muscle fibers in buffalo and cattle, indicating that myosin heavy chain type was not responsible for the difference in pH decline and tenderness between the buffalo meat and beef. This study demonstrated that the tenderness of water buffalo meat was superior to that of Brahman beef, which may have been due to the difference in pH decline and the subsequent effect on muscle protease activity.